CN115169265B - Method, system, equipment and medium for analyzing mixing coefficient based on numerical analysis - Google Patents

Method, system, equipment and medium for analyzing mixing coefficient based on numerical analysis Download PDF

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CN115169265B
CN115169265B CN202210900076.4A CN202210900076A CN115169265B CN 115169265 B CN115169265 B CN 115169265B CN 202210900076 A CN202210900076 A CN 202210900076A CN 115169265 B CN115169265 B CN 115169265B
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temperature difference
cold
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cfd
mixing coefficient
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CN115169265A (en
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陈曦
王啸宇
刘余
邓坚
冷贵君
李庆
杜思佳
刘伟
黄慧剑
杨小磊
刘卢果
张勇
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Nuclear Power Institute of China
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    • G—PHYSICS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract

The application discloses a mixing coefficient analysis method, a system, equipment and a medium based on numerical analysis, wherein the method comprises the following steps: acquiring a three-dimensional model of the fuel assembly with the lattice bundles; performing numerical analysis on the three-dimensional model of the fuel assembly by adopting a CFD analysis method to obtain a cold and hot channel temperature difference result based on CFD; modeling calculation is carried out under the same disclosure by adopting a sub-channel analysis method, so that a cold and hot channel temperature difference result based on sub-channels is obtained; and comparing the cold and hot channel temperature difference result based on CFD with the cold and hot channel temperature difference result based on the sub-channels, and determining the mixing coefficient under the current working condition. Compared with the existing mode of obtaining the mixing coefficient through experiments, the method can quickly and accurately obtain the mixing coefficient of the fuel assembly by utilizing a numerical simulation analysis method.

Description

Method, system, equipment and medium for analyzing mixing coefficient based on numerical analysis
Technical Field
The application belongs to the technical field of reactor thermal hydraulic design and safety analysis, and particularly relates to a mixing coefficient analysis method, system, equipment and medium based on numerical analysis.
Background
The accurate prediction of core critical heat flow density (Critical Heat Flux, CHF) is the core of the thermodynamic design of a reactor, and plays a vital role in the safety and economy of a nuclear reactor. In order to develop advanced fuel assemblies with independent intellectual property rights, to achieve higher critical heat flow density (CHF) and better hydrodynamic properties, improved designs are made for spacer grid structures and mixing foils.
In the thermodynamic and hydraulic design and safety evaluation of a pressurized water reactor core, subchannel analysis software is generally adopted, and a mixing coefficient is used as one of important input parameters for carrying out thermodynamic and hydraulic analysis calculation on a core subchannel by using a subchannel analysis program, and research results show that the mixing coefficient is mainly determined by the structure of a fuel assembly, is greatly influenced by the structure of a positioning grid, particularly a mixing wing of the grid, and has small influence on thermodynamic and hydraulic parameters such as system pressure, inlet temperature, mass flow rate and the like.
Heretofore, the blending coefficient of a fuel assembly has been generally obtained by a test, but since the test is extremely costly and time-consuming, particularly, a plurality of schemes need to be screened in the assembly structure optimizing stage, and it is impossible to conduct the test for each scheme, a method for obtaining the blending coefficient of the assembly efficiently and economically is required. With the rapid development of computational fluid dynamics analysis (CFD) in recent years, better research results are obtained in terms of simulating the flow heat exchange of fluid in a fuel assembly, and particularly, the single-phase CFD method has reached higher accuracy in the calculation accuracy of a rod bundle positioning grid flow field and a temperature field, has been widely applied to the prediction and analysis of the thermal hydraulic performance of the fuel assembly, and is necessary to try to develop CFD analysis in the early design stage, so that the CFD method is a substitute test to a certain extent and is used as an important reference for grid screening and test analysis.
Disclosure of Invention
In order to solve the problems of long time consumption and high cost of the conventional technology for obtaining the mixing coefficient of the fuel assembly through the test, the application provides a mixing coefficient analysis method based on numerical analysis for solving the problems.
The application is realized by the following technical scheme:
a method for analyzing a blending coefficient based on numerical analysis, comprising:
acquiring a three-dimensional model of the fuel assembly with the lattice bundles;
performing numerical analysis on the three-dimensional model of the fuel assembly by adopting a CFD analysis method to obtain a cold and hot channel temperature difference result based on CFD;
modeling calculation is carried out under the same disclosure by adopting a sub-channel analysis method, so that a cold and hot channel temperature difference result based on sub-channels is obtained;
and comparing the cold and hot channel temperature difference result based on CFD with the cold and hot channel temperature difference result based on the sub-channels, and determining the mixing coefficient under the current working condition.
As a preferred embodiment, the method for analyzing the CFD is used for carrying out numerical analysis on the three-dimensional model of the fuel assembly to obtain a cold and hot channel temperature difference result based on CFD, and specifically comprises the following steps:
performing geometric structure processing on the fuel assembly three-dimensional model to obtain a fluid domain part;
gridding the fluid domain part;
adopting a numerical simulation model, solving and calculating to obtain key parameters, judging whether the key parameters meet preset convergence conditions, if not, carrying out geometric structure processing and gridding processing again, otherwise, entering a subsequent step;
and calculating the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet according to the key parameters obtained by solving.
As a preferred embodiment, the present application performs gridding treatment on a fluid domain part, specifically:
for the fluid domain of the grid part, unstructured grids are adopted;
for the fuel rod portion fluid domain, a structured grid is employed.
As a preferred embodiment, the application adopts a sub-channel analysis method to carry out modeling calculation under the same disclosure to obtain a cold and hot channel temperature difference result based on sub-channels, and specifically comprises the following steps:
inputting the initial value of the mixing coefficient into a subchannel analysis program for modeling calculation to obtain key parameters of each subchannel under the same working condition;
and calculating the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet according to the obtained key parameters.
As a preferred embodiment, the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet is calculated by adopting the following formula:
wherein S represents the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet, T H Represents the average temperature of the outlet of the hot channel, T C Represents the average temperature, deltaT, of the cold channel outlet ave Indicating the inlet-outlet temperature difference.
As a preferred embodiment, the application compares the cold and hot channel temperature difference result based on CFD with the cold and hot channel temperature difference result based on sub-channels, and determines the mixing coefficient under the current working condition, specifically:
and taking the corresponding mixing coefficient as the corresponding mixing coefficient value under the current working condition when the relative values of the temperature difference of the cold and hot channels calculated by the two analysis modes relative to the average temperature difference of the inlet and the outlet are equal.
As a preferred embodiment, the method of the present application further comprises:
and obtaining the mixing coefficient values under a plurality of working conditions, and taking an average value as the mixing coefficient of the fuel assembly spacer grid.
In a second aspect, the application provides a mixing coefficient analysis system based on numerical analysis, which comprises a data acquisition module, a CFD analysis module, a subchannel analysis module and a comparison analysis module;
the data acquisition module is used for acquiring a three-dimensional model of the fuel assembly with the lattice bundles;
the CFD analysis module adopts a CFD method to carry out numerical analysis on the three-dimensional model of the fuel assembly to obtain a cold and hot channel temperature difference result based on the CFD method;
the sub-channel analysis module adopts a sub-channel analysis method, and performs modeling calculation under the same working condition to obtain a cold and hot channel temperature difference result based on the sub-channel analysis method;
the comparison analysis module compares the cold and hot channel temperature difference result based on CFD with the cold and hot channel temperature difference result based on the sub-channels, and determines the mixing coefficient under the current working condition.
In a third aspect, the present application proposes a computer device comprising a memory storing a computer program and a processor implementing the steps of the above-mentioned method of the present application when said computer program is executed by said processor.
In a fourth aspect, the present application proposes a computer-readable storage medium, on which a computer program is stored, which computer program, when being executed by a processor, carries out the steps of the above-mentioned method of the application.
The application has the following advantages and beneficial effects:
1. the application can quickly and accurately obtain the mixing coefficient of the fuel assembly based on the subchannel analysis program and the CFD method, and compared with the existing method for obtaining the mixing coefficient through a test, the application greatly reduces the required cost and obviously improves the research and development efficiency.
2. The application can provide accurate and reliable technical support and data support for screening of an autonomous fuel assembly grid and thermal hydraulic design work of a reactor.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:
FIG. 1 is a flow chart of a method according to an embodiment of the application.
Fig. 2 is a schematic diagram of a computer device according to an embodiment of the application.
Fig. 3 is a schematic view of an internally and externally arranged grid in accordance with an embodiment of the present application.
FIG. 4 is a schematic representation of the mixing coefficient results for an internally and externally arranged lattice obtained by the method of the present application.
Fig. 5 is a schematic view of a left-right layout grid according to an embodiment of the present application.
FIG. 6 is a schematic diagram of the results of blending coefficients for a side-to-side lattice obtained by the method of the present application.
Fig. 7 is a system schematic block diagram of an embodiment of the present application.
Detailed Description
For the purpose of making apparent the objects, technical solutions and advantages of the present application, the present application will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present application and the descriptions thereof are for illustrating the present application only and are not to be construed as limiting the present application.
Example 1
The mixing coefficient of the existing fuel assembly is usually obtained by means of tests, however, the test mode is high in cost and long in time consumption. Based on the above, the embodiment provides a mixing coefficient analysis method based on numerical analysis, and the method of the embodiment adopts a CFD numerical analysis technology and a subchannel analysis technology, so that the mixing coefficient can be rapidly and accurately determined, the analysis efficiency is greatly improved, and the test cost is reduced.
As shown in fig. 1, the method of this embodiment mainly includes the following steps:
a three-dimensional model of the fuel assembly with the lattice bundles is obtained.
And carrying out numerical analysis on the three-dimensional model of the fuel assembly by adopting a CFD method to obtain a cold and hot channel temperature difference result based on the CFD method.
And modeling calculation is carried out under the same working condition by adopting a sub-channel analysis method, so that a cold and hot channel temperature difference result based on the sub-channel analysis method is obtained.
And determining a mixing coefficient under the current working condition by comparing the cold and hot channel temperature difference result based on the CFD method with the cold and hot channel temperature difference result based on the sub-channel analysis method.
Further, the numerical analysis is performed on the three-dimensional model of the fuel assembly to obtain a temperature difference result of the cold and hot channels based on the CFD method, which specifically includes the following substeps:
and performing three-dimensional geometric structure processing on the fuel assembly three-dimensional model to obtain a fluid domain part. In order to ensure a grid with higher quality, on the premise of ensuring that a flow field is not influenced, simplified processing is carried out aiming at a complex geometric structure, and a fluid domain part is obtained, wherein the method comprises the following steps of:
1) Aiming at the fine modeling of the spring and the treatment of the line contact of the rigid spring bulge and the fuel rod, the line contact among the spring, the rigid spring bulge and the fuel rod is changed into non-contact, and a flow gap of 0.1mm is considered;
2) For analysis of the main attention heat transfer effect, a solid spring structure is considered, and on the premise of ensuring enough calculation accuracy, the grid quantity is greatly reduced, and the convergence effect of calculation is greatly improved;
3) In order to increase the calculation speed, only a geometric model of the outer surface of the fuel rod is built, and a heat source is added to the outer surface of the fuel rod.
The fluid domain portion is gridded. According to different complex degrees of the aggregate structure, different grid dividing methods are adopted respectively, and unstructured grids are adopted for the fluid domains of the grid part due to the complex structure; for the fuel rod partial fluid domain, the structure is simple and relatively regular, and a sweep grid is adopted. A new hybrid mesh bonding method is selected.
1) The grid area still adopts tetrahedral grids, the grid size is set in a global control and local encryption mode, a robust Octree (Octree) algorithm is selected to generate the tetrahedral grids, and the quality of the tetrahedral grids is improved through grid inspection and grid smoothing.
2) The grid of the bar bundle area is formed by axially sweeping quadrilateral surface grids generated at the interface, axial curve online grids are arranged according to the sizes of two dense ends and a sparse middle end, the quadrilateral surface grids at the interface are swept into hexahedral grid along the defined axial curve, grid nodes are combined at the interface, and the pyramid type grid transition is utilized to realize the communication of the calculation domain.
And adopting a numerical simulation model, solving and calculating to obtain key parameters, judging whether the key parameters meet preset conditions, if not, carrying out three-dimensional geometric structure processing and gridding processing again, and if so, carrying out subsequent steps. According to the actual operating condition of the reactor, proper boundary conditions such as inlet flow, temperature, outlet pressure and the like are set, and as the boundary layer turbulence in the rod bundle channel has obvious effect, the turbulence in the near-wall area and the transitional turbulence occupy a larger proportion, and various step structures are added, an SST turbulence model considering turbulent shear stress transportation is selected and used, and monitoring points such as adding speed and the like are added, so that the stability condition of the key parameter flow velocity is judged. Judging whether the residual error is smaller than 10 according to the convergence result of solving calculation -5 If not, the three-dimensional geometry processing and the gridding processing need to be performed again until the criterion is satisfied.
And obtaining the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet according to the parameters obtained by solving and calculating. The expression is as follows:
wherein S is CFD The relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet is shown,
T H 、T C and DeltaT ave The method comprises the following steps of:
wherein T is H For the average temperature of the outlet of the hot channel, T i For the outlet temperature of each thermal channel, T C Is a cold channelAverage outlet temperature, T j For the outlet temperature of each cold channel, N is the number of hot channels, M is the number of cold channels, W i For the outlet mass flow of the hot aisle, W j For cold channel outlet mass flow, T in For the inlet average temperature, deltaT ave Is the temperature difference between the inlet and the outlet.
Inputting the initial value of the mixing coefficient into a subchannel analysis program, and keeping the initial value consistent with an analysis object of the CFD method to perform modeling calculation, wherein the method comprises the following specific steps of:
1) Inputting main parameters corresponding to the calculation object, including heating power, inlet flow, outlet pressure, coolant inlet temperature and the like;
2) Inputting data related to the geometry of the bundle;
3) Inputting data of radial channel division and radial power distribution;
4) Inputting data of inlet flow distribution;
5) Axially divided resistance data is entered.
Firstly, according to the input requirements, the water properties (the heat conductivity and the constant pressure specific heat capacity are selectable), the slip ratio and the function for calculating the two-phase friction factor are subjected to the prior tabulation treatment, and then the mixed enthalpy energy conservation equation, the liquid phase energy conservation equation, the mass conservation equation, the axial momentum conservation equation and the transverse momentum conservation equation are solved for the whole field. And solving to obtain the pressure, specific enthalpy, axial mass flow rate and transverse mass flow rate at each axial node of each channel of the whole field.
The outlet temperature and the mass flow of each sub-channel under the same working condition are obtained through calculation, the automatic batch processing of relevant data such as flow and temperature is realized through writing a SHELL script, and the relative value S of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet is obtained through calculation by adopting the same calculation method as the CFD Subchannel program . It should be noted that, the temperature difference relative value of the cold and hot channels calculated based on CFD is a determined value, and the sub-channel program calculates a temperature difference relative value of the cold and hot channels for each mixing coefficient, so that the temperature difference relative value is a series of arrays corresponding to the mixing coefficients.
When S is Sub-channelsProcedure ＝S CFD And when the mixing coefficient corresponding to the relative value is calculated by adopting a sub-channel program, the mixing coefficient is the corresponding mixing coefficient value under the working condition.
According to the process, the mixing coefficient values under a plurality of working conditions are obtained, and the average value is obtained to be used as the mixing coefficient of the fuel assembly spacer grid.
The method provided by the embodiment of the application can efficiently develop the multi-scheme spacer grid mixing characteristic analysis, obtain the mixing coefficient for the thermal hydraulic analysis, and provide an optimization direction for the design of the grids so as to improve the thermal hydraulic performance of the fuel assembly and the reactor.
The embodiment also provides a computer device for executing the method of the embodiment.
As particularly shown in fig. 2, the computer device includes a processor, an internal memory, and a system bus; various device components, including internal memory and processors, are connected to the system bus. A processor is a piece of hardware used to execute computer program instructions by basic arithmetic and logical operations in a computer system. Internal memory is a physical device used to temporarily or permanently store computing programs or data (e.g., program state information). The system bus may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus. The processor and the internal memory may communicate data via a system bus. The internal memory includes a Read Only Memory (ROM) or a flash memory (not shown), and a Random Access Memory (RAM), which generally refers to a main memory loaded with an operating system and computer programs.
Computer devices typically include an external storage device. The external storage device may be selected from a variety of computer readable media, which refers to any available media that can be accessed by a computer device, including both removable and fixed media. For example, computer-readable media includes, but is not limited to, flash memory (micro-SD card), CD-ROM, digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computer device.
The computer device may be logically connected to one or more network terminals in a network environment. The network terminal may be a personal computer, server, router, smart phone, tablet computer, or other public network node. The computer device is connected to a network terminal through a network interface (local area network LAN interface). Local Area Networks (LANs) refer to computer networks of interconnected networks within a limited area, such as a home, school, computer laboratory, or office building using network media. WiFi and twisted pair wired ethernet are the two most common technologies used to construct local area networks.
It should be noted that other computer systems including more or fewer subsystems than computer devices may also be suitable for use with the application.
As described in detail above, the computer apparatus suitable for the present embodiment can perform the specified operation of the blending coefficient analysis method based on numerical analysis. The computer device performs these operations in the form of software instructions that are executed by a processor in a computer-readable medium. The software instructions may be read into memory from a storage device or from another device via a lan interface. The software instructions stored in the memory cause the processor to perform the method of processing group member information described above. Furthermore, the application may be implemented by means of hardware circuitry or by means of combination of hardware circuitry and software instructions. Thus, implementation of the present embodiments is not limited to any specific combination of hardware circuitry and software.
Example 2
In order to improve the accuracy of the mixing coefficient calculation, the sensitivity analysis result shows that the fuel assembly at least simulates three grids in the axial direction, and adopts an internal and external arrangement mode, namely a mode of 9 hot bars in the center and 16 cold bars in the periphery, as shown in fig. 3. To maximize radial power ratio, cool channels are defined as channels with cold bar heating surfaces to hot bar heating surfaces (e.g., 1-21, 24, 27, 30 in FIG. 2), and hot channels are defined as channels with cold bar heating surfaces less than or equal to hot bar heating surfaces (e.g., 22, 23, 25, 26, 28, 29, 31-36 in FIG. 2).
In this embodiment, the mixing coefficients of the internal and external arrangement grids shown in fig. 3 are analyzed by the method proposed in the above embodiment 1 to obtain the relative value of the cold-hot channel temperature difference relative to the average inlet-outlet temperature difference (i.e. the curve indicated by CFD shown in fig. 4) based on the CFD method shown in fig. 4 and the relative value of the cold-hot channel temperature difference relative to the average inlet-outlet temperature difference based on the sub-channel program (i.e. the curve indicated by the sub-channel program in fig. 4), and the intersection point of the two numerical curves is found, namely S Subchannel program ＝S CFD The mixing coefficient corresponding to the value is the mixing coefficient value under the working condition.
Example 3
In order to improve the accuracy of the mixing coefficient calculation, the sensitivity analysis result shows that at least three grids are simulated on the axis, and a left-right arrangement mode, namely a mode of 9 cold bars on the left side and 9 hot bars on the right side is adopted, as shown in fig. 5. Increasing the radial power ratio as much as possible, defining a cold channel as a channel with more cold rod heating surfaces than hot rod heating surfaces, such as 1-6, 17-21, 30 shown in fig. 5; the hot channels are defined as channels with a heating area of the cold bar smaller than that of the heating surface of the hot bar, such as 7-10, 13-16, 22-25, 26-29 shown in fig. 5.
In this embodiment, the mixing coefficients of the grids arranged left and right as shown in fig. 5 are analyzed by the method proposed in the above embodiment 1 to obtain the relative value of the cold-hot channel temperature difference relative to the average inlet-outlet temperature difference (i.e. the curve indicated by CFD as shown in fig. 6) based on the CFD method as shown in fig. 6, and the relative value of the cold-hot channel temperature difference relative to the average inlet-outlet temperature difference (i.e. the curve indicated by the sub-channel program as shown in fig. 6) based on the sub-channel program, so as to find the intersection point of the two numerical curves, i.e. S Subchannel program ＝S CFD The mixing coefficient corresponding to the value is the mixing coefficient value under the working condition.
Example 4
The present embodiment proposes a blending coefficient analysis system based on numerical analysis, as shown in fig. 7, the system includes: the system comprises a data acquisition module, a CFD analysis module, a sub-channel analysis module and a comparison analysis module.
The data acquisition module is used for acquiring a three-dimensional model of the fuel assembly with the lattice bundles;
the CFD analysis module adopts a CFD method to carry out numerical analysis on the three-dimensional model of the fuel assembly to obtain a cold and hot channel temperature difference result based on the CFD method;
the sub-channel analysis module adopts a sub-channel analysis method to carry out modeling calculation under the same working condition to obtain a cold and hot channel temperature difference result based on the sub-channel analysis method;
the comparison analysis module determines the mixing coefficient under the current working condition by comparing the temperature difference results of the cold and hot channels in the two modes.
The specific analysis process of each module unit in this embodiment is described in the above embodiment 1, and will not be described here again.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the application, and is not meant to limit the scope of the application, but to limit the application to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the application are intended to be included within the scope of the application.

Claims (8)

1. A method for analyzing a blending coefficient based on numerical analysis, comprising:
acquiring a three-dimensional model of the fuel assembly with the lattice bundles;
performing numerical analysis on the three-dimensional model of the fuel assembly by adopting a CFD analysis method to obtain a cold and hot channel temperature difference result based on CFD;
modeling calculation is carried out under the same disclosure by adopting a sub-channel analysis method, so that a cold and hot channel temperature difference result based on sub-channels is obtained;
comparing the cold and hot channel temperature difference result based on CFD with the cold and hot channel temperature difference result based on the sub-channels, and determining the mixing coefficient under the current working condition; performing numerical analysis on the three-dimensional model of the fuel assembly by adopting a CFD analysis method to obtain a cold and hot channel temperature difference result based on CFD, wherein the method specifically comprises the following steps:
performing geometric structure processing on the fuel assembly three-dimensional model to obtain a fluid domain part;
gridding the fluid domain part;
adopting a numerical simulation model, solving and calculating to obtain key parameters, judging whether the key parameters meet preset convergence conditions, if not, carrying out geometric structure processing and gridding processing again, otherwise, entering a subsequent step;
according to the key parameters obtained by solving, calculating to obtain the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet; the fluid domain part is subjected to gridding treatment, specifically:
for the fluid domain of the grid part, unstructured grids are adopted;
for the fuel rod portion fluid domain, a structured grid is employed.
2. The method for analyzing a mixing coefficient based on numerical analysis according to claim 1, wherein modeling calculation is performed under the same disclosure by adopting a sub-channel analysis method to obtain a sub-channel-based cold-hot channel temperature difference result, and the method specifically comprises the following steps:
inputting the initial value of the mixing coefficient into a subchannel analysis program for modeling calculation to obtain key parameters of each subchannel under the same working condition;
and calculating the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet according to the obtained key parameters.
3. The method for analyzing a mixing coefficient based on numerical analysis according to claim 1 or 2, wherein the relative value of the temperature difference of the cold and hot channels to the average temperature difference of the inlet and outlet is calculated by the following formula:
wherein S represents the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet, T H Represents the average temperature of the outlet of the hot channel, T C Represents the average temperature, delta, of the cold channel outletT ave Indicating the inlet-outlet temperature difference.
4. The method for analyzing a mixing coefficient based on numerical analysis according to claim 1, wherein comparing the cold-hot channel temperature difference result based on CFD with the cold-hot channel temperature difference result based on sub-channel, and determining the mixing coefficient under the current working condition comprises the following specific steps:
and taking the corresponding mixing coefficient as the corresponding mixing coefficient value under the current working condition when the relative values of the temperature difference of the cold and hot channels calculated by the two analysis modes relative to the average temperature difference of the inlet and the outlet are equal.
5. The method of claim 4, further comprising:
and obtaining the mixing coefficient values under a plurality of working conditions, and taking an average value as the mixing coefficient of the fuel assembly spacer grid.
6. The mixing coefficient analysis system based on numerical analysis is characterized by comprising a data acquisition module, a CFD analysis module, a subchannel analysis module and a comparison analysis module;
the data acquisition module is used for acquiring a three-dimensional model of the fuel assembly with the lattice bundles;
the CFD analysis module adopts a CFD method to carry out numerical analysis on the three-dimensional model of the fuel assembly to obtain a cold and hot channel temperature difference result based on the CFD method; performing numerical analysis on the three-dimensional model of the fuel assembly by adopting a CFD analysis method to obtain a cold and hot channel temperature difference result based on CFD, wherein the method specifically comprises the following steps:
performing geometric structure processing on the fuel assembly three-dimensional model to obtain a fluid domain part;
gridding the fluid domain part;
adopting a numerical simulation model, solving and calculating to obtain key parameters, judging whether the key parameters meet preset convergence conditions, if not, carrying out geometric structure processing and gridding processing again, otherwise, entering a subsequent step;
according to the key parameters obtained by solving, calculating to obtain the relative value of the temperature difference of the cold and hot channels relative to the average temperature difference of the inlet and the outlet;
the fluid domain part is subjected to gridding treatment, specifically:
for the fluid domain of the grid part, unstructured grids are adopted;
for a fuel rod portion fluid domain, a structured grid is employed;
the sub-channel analysis module adopts a sub-channel analysis method, and performs modeling calculation under the same working condition to obtain a cold and hot channel temperature difference result based on the sub-channel analysis method;
the comparison analysis module compares the cold and hot channel temperature difference result based on CFD with the cold and hot channel temperature difference result based on the sub-channels, and determines the mixing coefficient under the current working condition.
7. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1-5 when the computer program is executed.
8. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method according to any of claims 1-5.
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